KR102097704B1 - Method for selecting master in TDMA network and user terminal for thereof - Google Patents

Abstract

The present invention relates to a method for selecting a master based on competition between user terminals in a time division multiplex access (TDMA) network based on a communication frame including a control slot, a random access slot, and a user slot, which includes: allowing a user terminal participating in a network to set a state of the user terminal to an ′unknown′ state; determining whether a receive signal is present on a control slot in a first frame which is present, and determining that selection of the master is required when the receive signal is absent; waiting for transmission of a notification signal until an m^th slot, which the user terminal accesses, among M number of random access slots positioned next to a control slot comes, such that the user terminal is selected as the master, and transmitting a notification signal for notifying presence of the user terminal through the m^th slot when the notification signal of the user terminal is not received until a (m+1)^th slot; setting a state of the user terminal to a state of ′Provisional master′ when a notification signal of another user terminal is not received until an M^th slot comes after the transmission of the notification signal; and determining the state of the user terminal to a state of ′Master′, when a response signal is received from another user terminal through one of M number of random access slots next to the control slot after the transmission of a provisional master notification signal through a control slot in a next second frame. According to the present invention, when the master is absent in the TDMA network, the master may be rapidly and easily selected based on the effective competition between user terminals.

Description

Method for selecting master in TDMA network and user terminal therefor

The present invention relates to a method for selecting a master in a TDMA network and a user terminal therefor, and more specifically, a method for selecting a master in a TDMA network for selecting a master based on competition between users in a TDMA network and a user terminal therefor

In general, a TDMA (Time Division Multiple Access) network is operated by a broadcasting (Broadcasting) communication method.

Therefore, all users in the TDMA network are entitled to transmit only at the user slot time allocated to them, and there is always a listening state that receives and confirms even an unwanted signal at other times.

In addition, all users are entitled to transmit in their user slots, but at the same time, reception is impossible, so it is not possible to check whether there is a signal collision with another user.

Users in the TDMA network are divided into master and slave. The slaves are assigned user slots from the master in the network by notifying their presence in the contention period. At this time, the master checks for empty user slots and allocates appropriate user slots to slaves.

1 shows a communication frame structure of a TDMA network operating in a broadcasting environment. As shown in FIG. 1, a communication frame of a TDMA network generally includes a control slot, a plurality of random access slots, and a plurality of user slots, which correspond to the known ones.

The control slot is a time slot transmitted by the master, and the master may provide occupancy information (slot table) of each user slot to users through the control slot. The plurality of random access slots is a section in which users announce their existence by random access to request a slot allocation from the master. Subsequently, the master may allocate one of the user slots to the corresponding user. The user slot is a time slot that can be transmitted by users, and the user checks the slot table from the master and transmits his message at the slot time allocated to him.

However, when there is no master in the TDMA network, each user in the network cannot independently check the occupied state of the user slot and cannot check whether there is a collision between other users in the competition section.

Therefore, a master selection process is absolutely required in a TDMA network, and a more effective master selection technique is required in consideration of a broadcasting environment.

The technology underlying the present invention is disclosed in Korean Patent Publication No. 2016-0028939 (published on March 14, 2016).

An object of the present invention is to provide a master selection method and a user terminal therefor in a TDMA network capable of quickly and easily selecting a master when there is no master in the TDMA network.

In the present invention, in a master selection method using contention between user terminals in a TDMA network based on a communication frame including a control slot, a random access slot, and a user slot, a user terminal participating in the network sets its state to unknown. Step of determining whether a received signal exists on the control slot in the current first frame, and determining that master election is necessary if it does not exist, and M random located next to the control slot to be elected as the master. If the m-th slot (m = 0,1, ..., M) randomly accessed by the access slot waits for the transmission of the notification signal until the arrival, but the m-1th slot has not received the notification signal of another user terminal transmitting a notification signal informing of its existence through the m-th slot, and up to the M-th slot after transmission of the notification signal If the notification signal of another user terminal has not been received, setting one's state as a provisional master, and after transmitting the provisional master notification signal through the control slot in the next second frame, among the M random access slots after the control slot If a response signal from another user terminal is received through one, a master selection method is provided in a TDMA network including determining a status of the user as a master.

In addition, the user terminal may operate to randomly access one of the M random access slots in the frame every frame.

Further, the user terminal may operate to randomly access one of the M + L slots including M random access slots and L user slots located after the control slot, in order to be elected as a master. have.

In addition, the master selection method, the user terminal in the unknown state, while waiting for the transmission of the notification signal, if the notification signal of the other user terminal is received in at least one of m-1 th slot, the notification signal It may further include the step of abandoning the transmission and determining its own state as a slave state.

In addition, in the master selection method, the user terminal in the unknown state, when the notification signal of the other user terminal is received in at least one of the m + 1 to M th slots after the notification signal is transmitted, sets its state to the slave state. It may further include the step of determining.

In addition, if the master selection method is determined as the slave state, if the interim master notification signal is received by another user terminal in the control slot of the next second frame, one of the M random access slots after the control slot The method may further include transmitting the response signal to the random access slot.

In addition, each user terminal in the network, upon receiving the provisional master notification signal, transmits the response signal to it through a slot to which it is randomly accessed, but only when the status of the user is a slave state is the authority to transmit the response signal There is, it may be set to not respond when in an unknown state.

In addition, each user terminal in the network has a right to transmit the notification signal only when its state is an unknown state, and may be set not to transmit when it is a slave.

And, the present invention, in a user terminal competing with each other for master selection in a TDMA network based on a communication frame including a control slot, a random access slot, and a user slot, the state of their participation in the network is set to unknown. A setting unit, a determination unit determining whether a reception signal is present on the control slot in the current first frame, and determining that it is necessary to select a master if it does not exist, and M units located next to the control slot to be elected as a master Wait for the transmission of the notification signal until the m-th slot (m = 0,1, ..., M) randomly accessed from the random access slot arrives, but the notification signal of another user terminal is not received until the m-1th slot If not, the communication unit transmits a notification signal informing of its existence through the m-th slot, and even the M-th slot after transmission of the notification signal. If a notification signal of another user terminal has not been received, the controller includes a control unit that sets its status as a provisional master, and the communication unit transmits a provisional master notification signal through a control slot in the next second frame. After the provisional master notification signal is transmitted, if a response signal from another user terminal is received through one of the M random access slots after the control slot, it is possible to determine its own status as the master.

In addition, while waiting for transmission of the notification signal in the unknown state, the control unit abandons the transmission of the notification signal if the notification signal of the other user terminal is received in at least one of m-1 th slots. You can confirm your status as a slave status.

In addition, when the notification signal of the other user terminal is received in at least one of m + 1 to Mth slots after the notification signal is transmitted, the controller may determine its own state as a slave state.

In addition, after the communication unit is determined to be in the slave state, if the interim master notification signal is received by another user terminal in the control slot of the next second frame, one of the M random access slots after the control slot is randomly accessed. The response signal can be transmitted through one slot.

According to the present invention, if there is no master in a TDMA network based on broadcasting communication, the master can be quickly and easily elected through an efficient competition technique between user terminals currently participating in the network, and the elected performance and efficiency can be increased. It offers the advantage.

1 shows a communication frame structure of a TDMA network operating in a broadcasting environment.
2 is a diagram illustrating a TDMA network system according to an embodiment of the present invention.
FIG. 3 is a diagram showing the configuration of the user terminal illustrated in FIG. 1.
4 is a diagram illustrating a master selection method using contention between user terminals in a TDMA network according to an embodiment of the present invention.
5 to 9 are views showing various examples for explaining a master selection method according to an embodiment of the present invention.

Then, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice.

2 is a diagram illustrating a TDMA network system according to an embodiment of the present invention.

2, in a TDMA network system, a plurality of user terminals 100 are connected through a TDMA network. Here, according to the basic operation method of TDMA, all N user terminals 100 are operated in a broadcasting communication method.

Here, each user terminal 100 corresponds to a user in the network, and when any one of the users in the network is determined to be the master, the rest acts as a slave.

The master in the TDMA network allocates a user slot (time resource) to each slave. The slave can transmit the signal only in the corresponding user slot time allocated by the master, and it is always in the listening state for the other slot time, and only the signal can be received.

In addition, all users in the network know the time synchronization of an accurate time slot through a GPS pulse-per-second signal (1pps) signal, and all users operate in a broadcast communication method.

In this regard, it will be described with reference to FIG. 1 above. The communication frame structure of the TDMA network includes a control slot, a plurality of random access slots, and a plurality of user slots. Here, of course, each slot means a time slot.

The control slot is a time slot in which transmission authority is granted only to the master. At this time, the remaining users are in the listening state. The master broadcasts the signal it wants to send in the current frame through the control slot.

A plurality of random access slots, which are random access sections, are time slots that are randomly accessed by users participating in the network to request a slot allocation from the master, and the user broadcasts a signal informing of their existence at the corresponding slot time that they randomly accessed. Cast transfer. Of course, at this time, multiple users may randomly access the same slot at the same time and transmit their own notification signals at the same time. In this case, the signals are not normally received at the receiving side due to overlapping or collision of multiple signals.

The master can confirm the existence of the corresponding user from the signal normally received at the corresponding slot time, update the slot table (user slot occupancy information) by allocating one of the empty user slots as the time for the corresponding user, and slot table information Can be notified by broadcasting at the control slot time of the next frame.

At this time, users existing in the network can check the occupancy status of a plurality of user slots, as well as information on user slots (time resources) allocated to them based on the received user slot table.

The plurality of user slots located at the end of the frame are time slots to which transmission rights are respectively assigned to users. The user can broadcast and transmit a signal to be transmitted only through his / her assigned user slot, and is always in a listening state for the rest of the time.

However, if the user with the master role in the network is not determined or does not exist, master election is required. For example, master selection is required for cooperative driving between vehicles within a TDMA network based on a broadcasting operating environment. In this case, the user may mean a user terminal, a device, etc. installed in a vehicle and capable of communicating in a TDMA manner.

In the following embodiment of the present invention, when a master does not exist in a TDMA network environment based on broadcasting operation, a technique of competing between users using a random access section in a communication frame is attempted to select themselves as a master. We propose a new technique to select the master as quickly and effectively as possible through the network.

Each slot in a communication frame is generally composed of a preamble and a data section. However, in the present embodiment, the data section may include information to be transmitted, as well as identification information of a corresponding slot, identification information of a user allocated to the corresponding slot, and user status information.

Here, the user's status information is one of four states including 'unknown', 'slave', 'tentative master', and 'master', each of which is' 00 ',' 01 ',' 10 ',' It can be divided into status bits, such as 11 '. In the following exemplary embodiment of the present invention, it is assumed that when the user terminal transmits its data in a predetermined time slot, it also includes its own state information.

In addition, since the user terminal (user) transmits a signal in a broadcasting method, it is obvious that the signal transmission performed by each user hereinafter means broadcasting transmission. And, in the embodiment of the present invention, it is assumed that the user terminal operates to randomly access one of the M random access slots in the frame every frame.

3 is a diagram illustrating the configuration of a user terminal illustrated in FIG. 1, and FIG. 4 is a diagram illustrating a master selection method using contention between user terminals in a TDMA network according to an embodiment of the present invention.

3 and 4, the user terminal 100 according to an embodiment of the present invention includes a setting unit 110, a determination unit 120, a communication unit 130, and a control unit 140.

When the user terminal 100 newly participates in the network, the setting unit 110 sets the status of the user terminal 100 to unknown (S401). At this time, since the current state of the user is in an unknown state, as a result of the review in step S402, it corresponds to 'no', and the process immediately goes to step S403.

Then, the determination unit 120 checks the received signal on the control slot in the first frame, which is the current frame, and checks whether the received signal exists on the control slot (S403). If the received signal does not exist, it is judged that the master needs to be elected.

Here, of course, the presence of the received signal means the presence of the normally received signal. If a signal is transmitted (broadcasting) only from a single user terminal at a corresponding control slot time, a normally received signal will be present.

However, when a signal collision occurs due to simultaneous signal transmission (simultaneous broadcasting) from a plurality of user terminals at the corresponding control slot time, or when no user terminals in the network transmit signals at the control slot time There will be no normal received signal. As such, when there is no normal received signal, it means that there is no received signal.

As such, if there is no received signal on the control slot in the current frame, the user terminal 100 recognizes that there is no user with a provisional master or master role on the current network.

At this time, since no received signal is detected on the control slot, the result of the review in step S404 corresponds to 'no', and the procedure goes to step S405. In addition, since the user terminal 100 is currently in an unknown state, the result of the review in step S405 corresponds to yes, and the process goes to step S406.

Thereafter, the user terminal 100 undergoes a process of competing with another user terminal in order to be elected as a master. At this time, it is obvious that other user terminals also compete with each other while driving with the same algorithm.

Specifically, the user terminal 100 is notified until the arrival of the m-th slot (m = 0,1, ..., M) randomly accessed among the M random access slots located after the control slot in the first frame. Wait for the transmission, but it is determined whether the notification signal of the other user terminal is received up to the m-1th slot (S406).

Specifically, if a notification signal of another user terminal is not detected from the first slot to the m-1th slot, which is before the m-th slot, the communication unit 130 of the user terminal 100 informs its existence through the m-th slot The notification signal is transmitted (S407).

In the embodiment of the present invention, each user terminal in the network has a right to transmit a notification signal only when its state is in an unknown state, and is set not to transmit when it is a slave state. Since the current state is an unknown state, an alarm signal Since the transmission is possible, when the condition of step S406 is satisfied, an alarm signal can be transmitted.

However, as a result of the determination in step S406, if a notification signal of another user terminal is received in at least one of the 1st to m-1th slots, the controller 140 abandons the transmission of the notification signal and determines its state as a slave state. (S408).

Accordingly, the state information of the user terminal 100 is immediately switched from the existing 'unknown' state to the 'slave' state. Of course, the signal transmitted by the corresponding user terminal 100 from now on includes slave state information.

As described above, the user terminal 100, if there is another user terminal that first accesses and transmits a notification signal before the slot to which the user has accessed, gives the other user terminal an opportunity to select a master and gives up the master election. By immediately switching to the slave state, the time required to elect the master is reduced.

However, in the broadcasting environment, since the user terminal 100 can only transmit and receive signals in a slot accessed by the user, the user terminal 100 accesses the same random access slot as another user terminal in step S407. Even if the signal is transmitted, the user terminal 100 does not recognize the situation.

That is, each user randomly accesses any one of a plurality of random access slots in a random access section and transmits a signal, but in some cases, multiple users access the same random access slot simultaneously and transmit signals. In this case, the corresponding slot In the signal collision occurs, and the collisiond signal is difficult to be normally received by the remaining terminals, the remaining terminals recognize that there is no received signal in the corresponding slot.

For example, assuming a situation in which user terminals A and B simultaneously access the mth slot and user terminal C accesses the m + 2th slot simultaneously, the user terminals A and B simultaneously access the mth slot, respectively When the notification signal of is simultaneously transmitted, the user terminal C in the receiver's position at this time recognizes that there is no received signal in the m-th slot. Thereafter, if there is no received signal at all in the m + 1 th slot, the user terminal C transmits a notification signal informing of its existence in the m + 2 th slot.

This is a situation in which the user terminal A receives the notification signal from the user terminal C at a later time even though the user terminal A has transmitted its notification signal in the m-th slot. In this case, the user terminal A is unknown to the m-th slot accessed by the user terminal A. Another terminal of the simultaneous access to recognize that there was a signal collision.

That is, for example, in step S407 of FIG. 4, the user terminal 100 transmits its own notification signal in the 10th (m = 10) th slot, but receives the notification signal from another user in the subsequent 12th slot, It recognizes that there is a signal collision due to simultaneous access by multiple users in the 10th slot accessed by it. At this time, the user terminal 100 also abandons the master election and switches its state from the unknown state to the slave state, thereby reducing the time required for the master election in the network.

That is, when the user terminal 100 transmits a notification signal through the m-th slot (S407), it is confirmed that the notification signal of another user terminal is received in at least one of the next m + 1 to M-th slots Edo (S409), through the control unit 140 to determine its state as a slave state (S408).

However, if the user terminal 100 does not receive the notification signal of the other user terminal even to the last M th slot after the transmission of the notification signal, the user terminal 100 sets its state to the provisional master state (S410). The user in the temporary master state can be switched to the master or slave state through an additional process performed in the next frame.

Thereafter, the operation through the second frame, which is the next frame, is subsequently performed. It is apparent that the second frame also has the same frame structure as in FIG. 1.

After step S410, the process goes back to step S402. Since the current user terminal 100 is a provisional master state, the process goes to step S411.

Then, the user terminal 100 transmits a provisional master notification signal through the communication unit 130 indicating that it is a provisional master through a control slot in the second frame (S411).

Thereafter, it is determined whether a response signal by another user terminal (slave) has been received through at least one of the M random access slots after the control slot (S412), and if so, determines its own state as the master (S413). That is, if the response by the other user terminal is confirmed in only one of the M slots, the status of the user is determined as the master.

In the embodiment of the present invention, each user terminal in the network transmits a response signal through a slot to which it has been randomly connected when receiving a provisional master notification signal, but has the right to transmit a response signal only when its state is a slave state. If there is, it is set to not respond when it is in an unknown state. Therefore, all user terminals that have sent a response signal correspond to terminals in a slave state.

After being confirmed as the master, a master confirmation notification signal is transmitted through the control slot of the next third frame, so that all neighboring terminals participating in the network, that is, an unknown state and a slave state, can be informed of the existence of the master. After being determined as the master, it is sufficient to perform a role as a master in the TDMA network, that is, communication for allocating user slots of slaves.

If, as a result of the determination in step S412, a response signal has not been received, the process goes to step S401 to initialize its state to an unknown state and repeat the following process.

In a situation in which a response signal is not received, there may be a situation in which a signal collision occurs in the control slot due to the existence of an additional user in a temporary master state other than itself, and a situation in which multiple slaves access the same slot and a response signal collision occurs. However, if the total number M of random access slots is sufficiently large, the probability of the former case will be higher.

The following is a detailed description of the process after the determination of the slave in step S408. After the user terminal 100 is determined as the slave state, the operation through the second frame is also continuously performed.

After the determination of the slave, the process goes back to step S402, and since the determination result in step S402 corresponds to 'no', the process goes to step S403.

Here, the user terminal 100 checks the received signal on the control slot of the second frame (S403), and checks whether a temporary master notification signal by another user terminal is received at the control slot (S404).

If, as a result of the determination in step S404, a temporary master notification signal is received by another user terminal, the user terminal 100 again checks whether its state is a slave (S414).

Since the user terminal 100 is currently in a slave state, a response signal is transmitted (broadcasting transmission) through a slot that the user randomly accesses among the M random access slots after the control slot (S415). Accordingly, another user terminal in the temporary master state can be determined as the master state. For reference, the step S414 is provided because the user terminal has the authority to transmit the response signal only when the slave is in the slave state.

Hereinafter, the present invention will be described in more detail by exemplifying various situations. In addition, for convenience of description, it is assumed that the random access section is composed of a total of 5 slots (M = 5).

5 to 9 are views showing various examples for explaining a master selection method according to an embodiment of the present invention.

FIG. 5 shows a situation (Case 1) in which there are no user collisions in a random access section (competition section), including a user B and a user B requesting network participation. In the drawing, frame i (Frame i) means the i-th frame.

FIG. 5A defines a slot used by a user for random access or signal transmission in each frame, and FIG. 5B shows a user's transmission / reception operation and a user's state change history in each slot corresponding to FIG. 5A.

First, users A and B newly participating in the network set their state to an unknown state. In addition, as shown in FIG. 5A, users A and B who have confirmed that the signal is empty on the control slot of frame 1 are competing by randomly accessing any one slot in the random access section in order to become masters of each other.

Here, in the case of FIG. 5A, the user B randomly accesses the fourth slot (slot4) and the user A randomly accesses the fifth slot (slot5), which is an ideal case where there is no collision between users in the competition section.

From the user B's point of view, it is confirmed that a notification signal by another user has not been received up to the third slot located before the fourth slot (slot4) accessed by the user, and when the fourth slot (slot4) time reaches Broadcasts a notification signal informing of. Accordingly, in the fourth slot, user A receives the notification signal sent by user B. Referring to FIG. 5B, it can be seen that in slot 4, user B transmits and user A receives.

However, from the user A's point of view, the notification signal by the user B has already been broadcast in the fourth slot before the fifth slot to which he has accessed. Therefore, the user A receiving the notification signal from the user B in the fourth slot switches his state from the unknown state to the slave state as shown in FIG. 5B, and does not transmit his notification signal even when the fifth slot arrives.

Then, when the user B confirms that the notification signal by the other user has not been received until the fifth slot (slot5), which is the last slot in the random access section, the user B switches his state from the unknown state to the provisional master state. Referring to FIG. 5B, it can be seen that user B is changed to the provisional master state in slot5.

Next, in frame 2, the user B, which is the temporary master, broadcasts the temporary master notification signal through the control slot, and the user A receives it. Looking at frame 2 of FIG. 5B, it can be seen that in the control slot, user B is a transmission position and user A is a reception position.

Here, in frame 2, it is assumed that user A randomly accesses the third slot (slot3) of the random access section. User A receives the provisional master notification signal from the control slot and transmits a response signal to it through the third slot (slot3) that he randomly accesses. Looking at frame 2 of FIG. 5B, it can be seen that in slot 3, user A is in the transmission position and user B is in the reception position.

User B, which has received a response signal from another user in slot3, determines his state as the master. From then on, user B can act as a master in the network.

6 illustrates a situation (Case 2) in which there are two user terminals requesting network participation, including users A and B, and collisions between users in a random access section.

Referring to FIG. 6A, users A and B newly participating in the network set their own state to an unknown state, and users A and B confirming that the signal is empty on the control slot of frame 1 wants them to become masters of each other. Randomly access and compete in any one slot in the random access section.

Here, in the case of FIG. 6A, the users A and B are connected to the same slot (slot3), but each user does not know the simultaneous connection situation.

Each of users A and B confirms that a notification signal by another user has not been received before the third slot (slot3) that they randomly access, and transmits a notification signal informing of their existence in the third slot (slot3). do. Of course, since the notification signal is transmitted simultaneously, even if another user exists in the network, the corresponding signal is not normally received.

Subsequently, the users A and B both confirm that the notification signal by the other user has not been received until the last slot, the fifth slot (slot5), and switch their state from the unknown state to the provisional master state. Looking at frame 1 of FIG. 6B, it can be seen that both slots A and B have changed to the provisional master state.

Subsequently, in frame 2, users A and B, which are temporary masters, simultaneously transmit the temporary master notification signal through the control slot. However, there are no users other than users A and B in the current network, and even if they exist, the corresponding signal cannot be transmitted because the corresponding signal is not received due to signal collision due to simultaneous transmission.

Users A and B, respectively, who have confirmed that no response signal has been sent even to the last 5th slot, change their state back to the unknown state. This can be seen in Frame 3. In frame 3, users A and B confirm that the signal is empty in the control slot, and perform random access, respectively.

6A and 6B, in frame 3, user A randomly accesses the second slot (slot2) and user B randomly accesses the fifth slot (slot5). In this case, user A first transmits a notification signal. User A becomes a provisional master, and user B becomes a slave.

Subsequently, in frame 4, user A transmits a provisional master notification signal through the control slot, and receives a response signal from user B to slot 1 to confirm his state as the master.

Next, FIG. 7 shows a situation (Case 3) in which there are three user terminals including users A, B, and C, and there is no collision between users in a random access section. FIG. 7 is different in that frame C newly requests user C to join the network.

Since the operation principle in frame 1 is the same as that of FIG. 5, a detailed description is omitted. In addition, in frame 2, user C exists in an unknown state because he is new to the network.

The user A determined to be the temporary master state in frame 1 broadcasts the temporary master notification signal at the control slot time in frame 2, and both users B and C receive it as shown in FIG. 7B.

Here, in this embodiment, only the user in the slave state has the authority to transmit the response signal, so only the user B in the slave state transmits the response signal, as shown in FIG. 7B, and it can be seen that the user C in the unknown state does not respond.

Of course, the user C newly participating in frame 2 confirms that the signal exists on the control slot of frame 2, and therefore does not transmit a notification signal for notifying his presence. The rest of the operation refers to the principle described above.

Next, FIG. 8 shows a situation (Case 4) in which there are three user terminals including users A, B, and C, and collisions between users exist in a random access section, and a new network participating user occurs during master election. .

Users A and B newly participating in the network set their state to an unknown state, confirm that the signal is empty on the control slot of frame 1, and randomly access and compete in one slot in the random access section.

At this time, in frame 1, users A and B are connected to the same slot (slot3), and the third slot (slot3) simultaneously transmits a notification signal informing of their existence. Then, the users A and B both confirm that the notification signal by the other user has not been received until the fifth slot (slot5), which is the last slot, and switch their state from the unknown state to the provisional master state. Referring to frame 1 of FIG. 8B, it can be seen that in slot 5, both users A and B have been changed to the provisional master state.

Next, in frame 2, new user C participates, and user C is in an unknown state. In this frame 2, users A and B simultaneously transmit a provisional master notification signal through a control slot, and user C enters a position to receive the signal.

However, due to the collision of the two signals, the corresponding signal is not normally received by the user C, so the user C recognizes that the control slot in frame 2 is empty. Accordingly, the user C operates to transmit a notification signal for notifying of his existence through the fourth slot (slot4) that he randomly accesses, in order to be elected as a master. The notification signals of the user C are received by the users A and B.

That is, looking at frame 2 of FIG. 8B, it can be seen that in slot 4, user C is a transmission position, and users A and B are a reception position. As described above, after transmitting the interim master notification signal, the users A and B may recognize that a collision has occurred on the control slot when the notification signal other than the response signal is received from the other user. Switch to

That is, users A and B, which have received the notification signal in slot 4 of frame 2, change their state from the provisional master to the slave state. Of course, in frame 2, user C confirms that the notification signal by the other user has not been received until the fifth slot (slot5) and switches his state to the provisional master.

In frame 3, user C sends a tentative master notification signal through the control slot, and users A and B in the slave state receive it. Users A and B transmit their response signals through slots (slot2 and slot5) randomly accessed in frame 3, respectively. At this time, when the response signal is received from only one of the random access slots, the user C immediately determines his state as the master state, so it can be seen that the slot 2 has been confirmed as the master.

Next, FIG. 9 shows a situation (Case 5) in which there are three user terminals including users A, B, and C, and collisions between users exist.

In frame 1, user A simultaneously accesses the first slot (slot1), and users B and C access the third slot (slot3), but user B and C transmit the notification signal because user A transmitted the notification signal in slot1. Gives up and switches its state from an unknown state to a slave state.

User A confirms that the notification signal by another user has not been received until the last slot, the fifth slot (slot5), and switches his state from the unknown state to the provisional master state.

In frame 2, user A transmits a provisional master notification signal through the control slot, and users B and C receive it. In response, users B and C transmit a response signal in a slot 4 randomly accessed by them. However, since users B and C simultaneously transmit response signals through the same slot, the response signals are not normally received by user A due to signal collision.

User A determines that the response signal has not been received even up to the last fifth slot (slot 5), and then switches his state back to the unknown state. In frame 4, user A is in an unknown state, and users B and C are in a slave state.

Here, in the embodiment of the present invention, each user can transmit a notification signal informing of their existence when the control slot in the frame is empty, but it can be transmitted only in an unknown state and is set not to transmit in a slave state.

Therefore, although the control slot is empty in frame 3, only user A transmits a notification signal and users B and C operate not to transmit a notification signal. In frame 3, user A transmits a notification signal through a second slot (slot2) that he randomly accesses, and users B and C receive it. User A checks that there is no notification signal from another user until the last 5th slot (slot5) and changes his status to the provisional master.

Thereafter, user A transmits a provisional master notification signal through the control slot of frame 4, and users B and C receive it. At this time, the response signal is first received from the user C randomly accessing slot1, and the user A, which has received the response signal, determines his state as the master.

The above embodiments of the present invention exemplify competing through a random access slot in a random access section, but the present invention is not limited thereto.

That is, the user terminal 100 may operate to randomly access one of the M + L slots including M random access slots and L user slots located after the control slot, in order to be elected as a master. have.

Since the plurality of user slots located after the random access section in the communication frame structure of FIG. 1 is a section that is not used and wasted until the master is elected, the possibility of collision in the competition section is reduced when additional user slots are utilized. Furthermore, it is possible to minimize the selection time of the master.

According to the present invention as described above, if a master does not exist in a TDMA network operated in a broadcasting communication environment, a master can be quickly and easily elected through an efficient competition technique between user terminals currently participating in the network and elected. It has the advantage of improving performance and efficiency.

Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100: user terminal 110: setting unit
120: judgment unit 130: communication unit
140: control unit

Claims (15)

In the master selection method using the competition between user terminals in a communication frame-based TDMA network including a control slot, a random access slot, a user slot,
A user terminal participating in a network setting its state to unknown;
Checking whether a received signal exists on a control slot in the current first frame, and if not, determining that master election is necessary;
To be elected as the master, wait for the transmission of the notification signal until the m-th slot (m = 0,1, ..., M) randomly accessed from the M random access slots located after the control slot arrives, m -If a notification signal of another user terminal is not received up to the first slot, transmitting a notification signal informing of the existence of the user through the m-th slot;
Setting the status of the user as a provisional master if the notification signal of another user terminal is not received even in the Mth slot after transmission of the notification signal; And
If a response signal from another user terminal is received through one of the M random access slots after the control slot after transmitting the provisional master notification signal through the control slot in the next second frame, determining its status as the master step
Master selection method in a TDMA network comprising a. The method according to claim 1,
The user terminal,
A master selection method in a TDMA network that operates to randomly access one of the M random access slots in a frame every frame. The method according to claim 2,
The user terminal,
A master selection method in a TDMA network that operates to randomly access one of all M + L slots including M random access slots and L user slots located after the control slot in order to be elected as a master. The method according to claim 1,
While waiting for the notification signal to be transmitted by the user terminal in the unknown state, if the notification signal of the other user terminal is received in at least one of the m-1th slots from 1, it abandons the transmission of the notification signal and returns its status. To determine the status as a slave
Master selection method in the TDMA network further comprising. The method according to claim 1,
When the user terminal in the unknown state receives the notification signal of the other user terminal in at least one of m + 1 to M th slots after the notification signal is transmitted, determining the status of the user terminal as a slave state
Master selection method in the TDMA network further comprising. The method according to claim 4 or claim 5,
After determining to the slave state, if the interim master notification signal is received by another user terminal in the control slot of the next second frame, through the randomly accessed slot among the M random access slots after the control slot Transmitting the response signal
Master selection method in the TDMA network further comprising. The method according to claim 1,
Each user terminal in the network,
When the temporary master notification signal is received, the response signal is transmitted through a slot accessed by the user,
A method for selecting a master in a TDMA network set to have no response when the state of the slave is in the slave state and transmits the response signal only. The method according to claim 1,
Each user terminal in the network,
A method of selecting a master in a TDMA network that is set to not transmit when it is in the slave state when it is in the slave state. In a user terminal competing with each other for selecting a master in a TDMA network based on a communication frame including a control slot, a random access slot, and a user slot,
A setting unit configured to set one's state participating in the network as unknown;
A determination unit determining whether a reception signal exists on the control slot in the current first frame, and determining that master election is necessary if it does not exist;
To be elected as the master, wait for the transmission of the notification signal until the m-th slot (m = 0,1, ..., M) randomly accessed from the M random access slots located after the control slot arrives, m -A communication unit that transmits a notification signal informing of its existence through the m-th slot when the notification signal of another user terminal is not received up to the first slot; And
If the notification signal of another user terminal is not received even in the M-th slot after transmission of the notification signal, a control unit for setting its status as a provisional master includes
The communication unit,
Transmitting the interim master notification signal through the control slot in the second frame,
The control unit,
If the response signal by another user terminal is received through one of the M random access slots after the control slot after the provisional master notification signal is transmitted, the user terminal in the TDMA network to determine its status as the master. The method according to claim 9,
The user terminal,
A user terminal in a TDMA network that operates to randomly access one of the M random access slots in a frame every frame. The method according to claim 9,
The control unit,
While waiting to transmit the notification signal in the unknown state, if the notification signal of the other user terminal is received in at least one of m-1 th slots, the transmission of the notification signal is abandoned and its status is slave status. User terminal in the TDMA network to confirm. The method according to claim 9,
The control unit,
When the notification signal of the other user terminal is received in at least one of m + 1 to Mth slots after the notification signal is transmitted, the user terminal in the TDMA network that determines its status as a slave state. The method according to claim 11 or claim 12,
The communication unit,
After determining to the slave state, if the interim master notification signal is received by another user terminal in the control slot of the next second frame, through the randomly accessed slot among the M random access slots after the control slot A user terminal in a TDMA network that transmits the response signal. The method according to claim 9,
Each user terminal in the network,
The user terminal in the TDMA network set to not respond if it has the right to transmit the response signal only when its state is the slave state, and if it is in the unknown state. The method according to claim 9,
Each user terminal in the network,
If there is no received signal on the control slot in the first frame, transmits a notification signal informing of its existence,
A user terminal in a TDMA network that is set to not transmit when it is in the slave state and has the authority to transmit the notification signal only when its state is in the unknown state.

Images